Weekly update for September 11
Show and Tell
September 11
Upload your progress (using RStudio) 1/2
- Make sure that you connect RStudio and Github. Click here.
- Go to File -> New Project -> Version Control -> Git.
- Fill out:
- Go to File -> Open file… -> 02_weekly-updates/update-2017-09-11.Rmd
Upload your progress (using RStudio) 2/2
Add a few slides and save. You can copy the format of other slides or make something more sophisticated.
Click ‘Knit’ button.
Commit and push your changes on ‘update-2017-09-11.Rmd’ and ‘update-2017-09-11.html’ in the Git section.
shinyapps repo
The shinyapps repo on github is a sandbox for our different shiny applications:
bulletr, x3p-viewer, and groove-finder are on there at the moment.
ICFIS Workshop
Title: “Elements of Forensic Science for Forensic Practitioners”
Lessons learned:
- Siloization - different disciplines have own language and terms
- “Hierarchy of Propositions”
- Source level - is a person the source of the evidence? (CSAFE can help most here, imho)
- Activity level - how did that evidence get there (investigators)
- Offense level - did a criminal act occur? (judicial system)
ICFIS Workshop (cont’d)
More lessons learned:
- Generic Model for forensic evidence analysis
- Feature selection (relevant & useful features)
- Distortion assessment (intra-source variability; which differences matter?)
- “Matching” step (correspondence; how strong of a match?)
- “Significance” of the “match” (discriminability; how discriminating is the “match”?)
- Decision (reporting; LR, frequency, categorical scale?)
- Quality control (verification, technical review)
ICFIS Workshop, Fingerprints
- Fingerprint evidence protocol ACE-V
- Analysis - information gathering step (1 + 2 above)
- Comparison - side-by-side of latent v. known (3 + 4 above)
- Evaluation - decision making (5 above)
- Verification - 2nd analyst repeats ACE (6 above)
- GYRO marking of features - subjective qualitative assessment of uncertainty
- Green = High confidence
- Yellow = Medium confidence
- Red = Low confidence
- Orange = Annotations after viewing known print
ICFIS Workshop, Trace Evidence
Q: What is trace evidence?
A: Microscopic debris easily transferred from one location to another
- “We will attempt to physically match anything”
- Paint, tape, glass, fiber, etc.
- Flowchart of analysis:

ICFIS Workshop, DNA
- PCR-STR: polymerase chain reaction short tandem repeats
- Replicate a DNA sample, count occurrences of STR alleles at 23 loci
- One mismatched loci is enough to eliminate (in single-source sample)
- Markers for sex are DYS391, Chromosomes (X,Y), one other location
- SE33 is a very discriminating location. more info here
- At most 2 values per location - one from mom, one from dad.

MTurk Preliminary Results 1
